Clutches

ABSTRACT

Various embodiments of overrunning clutches are described. Each clutch is of the type which incorporates mutually interleaved friction plates; and mutually separable annular pressure plates connected respectively to driving and driven members and having between them actuating means in the form of ball-and-ramp actuators which are sensitive to the direction of relative rotation of the pressure plates and consequently of the driving and driven members. In order to improve the sensitivity of the clutch, the pressure plates are lightly spring biassed by springs which act on the pressure plates in opposite circumferential directions which correspond with a tendency for the pressure plates to separate. The springs place the clutch in a pre-loaded condition and so improve the sensitivity, and also take up wear which may occur in the friction plates or pressure plates. Embodiments incorporating both tension and compression spring are described.

United States Patent Primary Examiner-William F. ODea AssistantExaminer-Randall Heald Attorney-Mason, Fenwick & Lawrence Webb [4 Aug.1, 1972 1 s41 CLUTCHES [57] ABSTRACT {72] Inventor: Oswald Webb whlfleyrEngland Various embodiments of overrunning clutches are [73] Assignee;Han-y Ferguson Research Limited described. Each clutch is' of the typewhich incorporates mutually interleaved friction plates; and mu- [22]filed: 1970 'tually separable annular pressure plates connected [21]Appl. No.: 82,665 I respectively to driving and driven members andhaving I between them actuating means in the form of balland-rampactuators which are sensitive to the [30] Foreign Application Mydirection of relative rotation of the pressure plates and Oct. 22, 1969Great Britain ..5l,666/69 consequently of the driving and drivenmembers. In

order to improve the sensitivity of the clutch, the pres- US. Cl. B, ureplates are spring by springs which Int. ..Fl6d act on the pressureplates in opposite circumferential [58] Field of Search ..192/12 B, 54,41, 52 directions which correspond i a tendency f the pressure plates toseparate. The springs place the [56] References Cited clutch in apre-loaded condition and so improve the UNITED STATES PATENTSsensitivity, and also take up wear which may occur in the frictionplates or pressure plates. Embodiments in- 2,915,156 12/1959 Horn..192/41 corporafing both tension and compression spring are 3,477,30211/1969 Webb ..192/12 Bv describfli v 3,118,292 1/1964 Schrbter et al...192/54 J 6 Claims, 7 Drawing Figures PATENTEMM I91 3.680.673 sum 1-[IF 4 I mu) lnvenlor OSWALD WEBB ma m W1 A llorney S PAIENTEDMIB H912 I3.680.673

sumsnra lnvenlor OSWALD WEBB.

Attorney;

P'A'TENTEDAus H972 3.680.673

SHEET '4- UF 4 Inventor O WAL D WEBB masau 'wm K.

Attorney 5 CLUTCHES This invention relates to overrunning clutches.

More particularly, the invention is concerned with such overrunningclutches which permit the driven member to overrun the driving member atleast in one direction of rotation, and which incorporate a fractionclutch arranged mechanically in series with means sensitive to therelative direction of rotation of the members with respect to oneanother and adapted so as to very torsional capacity of the frictionclutch in accordance with changes in the said relative direction ofrotation. Thus, during drive, torsional capacity of the friction clutchis increased whereas, during overrun, torsional capacity of the frictionclutch is reduced and the clutch slips. v

According to the present invention there is provided an overrunningclutch comprising rotatable driving and driven members, drive meansoperatively interposed between the driving and driven members, the saidmeans including a first pressure plate, connecting means forestablishing a driving connection between the driving member and thefirst pressure plate, a shiftable second pressure plate, a frictionclutch of variable torsional capacity between the driven member and theshiftable pressure plate for establishing a driving connection betweenthe driven member and the shiftable pressure plate, the said pressureplates having mutually co operable camming means thereon for forcing thepressure plates apart and consequently increasing torsional capacity ofthe friction clutch when the driv-' ing and driven members andconsequently the pressure plates tend to rotate relatively with respectto one another in one relative direction, a casing surrounding the saiddrive means and rotatable about the axis of the overrunning clutch,second connecting means placing the casing in diving connection with theshiftable pressure plate, and a spring acting on the pressure plates soas to tend to rotate the plates relatively with respect to one anotherin the said one relative direction, said spring having one end thereofconnected to the first pressure plate and theother end thereof anchoredto the casing. The present invention is also an improvement in ormodification of the invention set forth in the complete specification ofour British Pat. No. 1,185,043; and at the same time is an improvementin or modification of the invention set forth in the completespecification of our British Pat. No. 35 365/68.

Embodiments of the present invention will now be described, by way ofexample, with reference to the drawings in which:

FIG. 1 is a diagrammatic representation of an overrunning clutch inaccordance with the present invention;

FIG. 2 is a part-sectional side elevation of a practical embodiment ofthe overrunning clutch of FIG. 1;

FIG. 3 is a sectional end view on the line III-III in FIG. 2;

FIG. 4 is a diagrammatic representation of an overrunning clutchcorresponding with that illustrated in FIG. 4 of our British Pat. No.1,185,043, but modified in accordance with the present invention.

FIG. 5 is a diagrammatic representation of aN overrunning clutchcorresponding with that illustrated in FIGS. 1, 4 and 5 of our BritishPat. 1,236,981, but

modified in accordance with the resent invention;

FIG. 6 is a part-sectional side elevation similar to FIG. 2, butincluding a modification.

TI-ie broken outlines in FIGS. 1 and 2 show a modification of the fullline drawings such as to render FIGS. 1 and 2 similar to FIGS. 1 and 2of our British Pat. No. 1,185,043 modified in accordance with the resentinvention.

Reference has been made above to our British Pat. Nos. 1,185,045 and1,236,981. and it is to be understood that such reference is intended toimpart into this specification the entire disclosure of the completespecifications of these earlier proposals.

In FIGS. 2 and 3 of the drawings, ignoring for the moment the brokenoutlines in FIG. 2, an overrunning clutch in accordance with the presentinvention consists of rotatable driving and driven members in the formof tubular shafts 2 and 3 respectively, mutually opposed first andsecond axially shiftable pressure plates 4 and 5 having camming means inthe form of balls 6 (only one ball is shown in FIG. 2) which arereceived in circumferentially arranged ramped grooves 7, (see FIG. 1)friction clutches 8 and 9 in the form of sets of interleaved frictionplates and tension springs 10 arranged so as to tend to rotate thepressure plates 4 and 5 relatively with respect to one another so thatthe balls 6 and ramped grooves 7 interact to urge the pressure platesaway from one another.

The friction clutches 8, 9 and the pressure plates 4, 5 are mutuallyco-axially arranged within a cylindrical housing 11, the clutches 4, 5being backed, respectively, by annular abutment plates l2, l3, andneedle rollers l4, 15. The needle rollers 14 bear against an annular endplate 16 retained by a circlip l7, and the needle rollers 15 bearagainst a ring 18 which is retained by a circlip 19 through an annularpacking-piece 20 and a second annular end-plate 21. In the frictionclutches 8, 9 inner plates of the sets of interleaved friction platesare splined, respectively, to the shafts 2,3 and outer" plates haveradial projections 22 (see FIG. 3) received in axially extending slotsin cylindrical hollow cage portions 4A, 5A formed integrally with thepressure plates 4, 5. The ring 18 is provided with radial projections18A which extend through the slots of the cage portion 5A, and whichextend also through corresponding slots in the housing 11. Thus, thepressure plate 5 is rotationally in driving connection with the housing11. The springs 10 are arranged to act in a circumferential directionand lie against the outer surface of the casing 11. One end of eachspring 10 is anchored to the housing 11 by means of radially inwardlyprojecting lugs 23 on an annular shroud 24 secured to the casing 11,while the other end of each spring 10 is connected to the pressure plate4 by way of links 25 which project through slots 26 in the housing 11and engage hooked formations on the radial projections 22 of one of theouter plates of the friction clutch 8. Thus, the springs 10, in effect,tend to rotate the pressure plates 4, 5 relatively with respect to oneanother in one relative direction, namely that in which the balls 6 andramped grooved 7 interact to move the pressure plates away from oneanother and so pre-load the friction clutches 8, 9 thus ensuringsensitivity of the pressure plates 4, 5 to the relative direction ofrotation of the shafts 2, 3 with respect to one another.

Operation of the overrunninG clutch as so-far described will now beexplained with reference to FIG.

l inwhich parts corresponding to those of FIGS. 2 and 3 are given thesame reference numerals as are used in relation to FIGS. 2 and 3.

In FIG. 1, ignoring for the'moment the broken outlines, it may be seenthatwhen both the driving and driven shafts 2 and 3 are rotatinganti-clockwise, as viewed from the lefthand side of FIG. 1, the drivenshaft 3 can overrun the driving shaft 2, during which overrun slipoccurs in the friction clutch 9, both fric-' tion clutches 8, 9 beingonly relatively lightly preloaded by the springs 10, Immediately therotational speed of the driven shaft 3 tends to drop below that of thedriving shaft 2, the pressure plates 4, 5 will tend to b'e'moved awayfrom oneanother by interaction of the balls 6 and ramped grooves 7 andso increase the torsional'capacity of the friction clutches, 8 9 thatthe coupling will lock-l and so establish a driving connection betweenthe two shafts. Similarly, if a rotational oscillating or indixingmovement is applied to the shaft 2, the shaft will be turned by theshaft 2 only on every alternate stroke, that is only by every stroke inan anti-clockwise direction. Under these, and under all other operatingconditions of the overrunning clutch, the springs 10 maintain apre-loading force on the friction clutches. In addition, because of themanner in which the springs 10 are arranged, it will be appreciated thatthe pressure plates 4, 5 are biassed so that they tend at all timestoadopt a position with respect to one another such that any lost-motionin the ball-and-ramp arrangement is kept to a minimum. This isadvantageous in that the sensitivity of the overrunning clutch ismaintained at an optimum and in that any wear which might occur betweenelements of the friction clutches 8, 9 is automatically compensated byvirtue of the springs 10 continually adjusting therotational positioningof the pressure plates with respect to one another so that the balls 6are never allowed to lie slackly in the groves 7. A further advantage isderived from the fact thatthe springs 10, being relatively long,

. may have arelatively low rate with the result that the valueofme-loading. force applied to the friction clutches8, 9 may bemaintained within close tolerances despite any wear which may occur.

Considering now the broken outlines in FIG. 1 and 2, these illustrate amodification wherein a one-way brake Is provided for the purpose ofcontrolling rotational movement of the pressure plate 5. In FIG. 2, theoneway brake is in the form of a sprag clutch 27 interposed between anextension 11A of the housing 11 and a collar 28 adapted to be heldstationary or earthed" with respect to, for example, a fixed casing ofpart of a vehicle transmission. The spring clutch 27 permits the housing1 1 to rotate only in the anti-clockwise direction and this arrangementrenders the pressure plate 5 non-sensitive to overrunof the shaft 3 whenboth shafts are rotating clockwise, thus the shaft 3 may overrun theshaft 2 in both directions of rotation. In this connection, reference ismade to our British Pat. No.

1,185,043 wherein the operation and application of a coupling similar tothe above-described modification is described in greaterdetail. Incomparing the coupling proposed herein with the overrunning clutchproposed inthe last-mentioned reference, it will be noted that thesprings 10 replace the compression springs 21 of FIG. 2 of thereference, and that they also replace springs 28 of FIG. 7 of thereference.

The last-mentioned-replacement is further explained with reference tothe present FIG. 4, in which parts corresponding to those in FIG. 1 aregiven the reference" ward thrust on pressure plate 5 when the pressureplate 5 rotates or tends to rotate in a clockwise direction. Thisleftwardthrust reduces the torsional capacity of the friction clutch 9and so enables the shaft 3 to rotate clockwiseunder certain conditions.This is explained more fully in our British Pat. No. 1,185,043 whereinis also explained the desirability of incorporating a spring arranged toseparate the ramp faces 58 and 18B promptly. In the present case, thesprings 10 achieve the desired separation of the ramp faces 58 and 188since one end of each spring 10 is anchored to the casing 11 andtherefore acts on the outermost portions of the projections 18A, whilethe other'end of each spring 10 acts on the pressure plate 5, andtherefore on the cage 5A, by way of the balls 6 and ramped grooves 7.

FIG. 5 illustrates a further modification wherein, in addition to theprovision of a one-way brake and ramp faces, there are also providedmutually co-operable stops on the pressure plate 4 and on the runningmember of the brake respectively for the purpose set forth in ourBritish Pat. No. 1,236,981, namely, in brief, for the principal purposeof limiting the effect of the ramp faces 58 and 1813 increasing thetorsional capacity of the friction clutch 8. In FIG. 5, partscorresponding to those in FIG. 1 and 4 are given the pose as the springs10in FIG. 4, namely to pre-load the friction clutches 8 and 9 and tourge the ramp faces 58 and 18B apart.

FIG. 6 illustrates yet a further modification of the overrunning clutchdescribed with reference to FIGS. 2, and 3, and parts corresponding tothose in FIGS. 2 and 3 are given the reference numerals used in FIGS. 2and 3. Here, only one friction clutch is employed, namely the frictionclutch 9. The pressure plate 4 is splined directly to the shaft 2 by wayof an internally splined collar portion 4D which also bears directly onthe needle rollers 14. The springs 10 are. attached directly to thepressure plate 4. Apart from these changes, the construction andoperation of the overrunning clutch of FIG. 6 is the same as has beendescribed with reference to FIGS. 2 and 3.

I In the overrunning clutches herein described with reference to FIGS.2, 3 and 6, the provision of the ring 18 is principally for the purposeof making possible the modifications described with reference to FIGS.1, 4 and 5 in that the projections 18A provide a convenient means ofachieving interconnection between the pres sure plate 5 and the casing l1.

In the foregoing and in the appended claims, it is to be understoodthat, in reference to rotatable driving and driven members, the wordsdriving" and driven are used conveniently to distinguish between therotatable members concerned and are to be interpreted in a mannerclearly comprehended in the proposals described and imported by specificreference. For example, it is to be understood that an overrunningclutch in accordance with the present invention permits both members tobe driven at different speeds.

We claim:

1. An overrunning clutch comprising rotatable driving and drivenmembers, drive means operatively interposed between the driving anddriven members, the said means including a first pressure plate,connecting means for establishing a driving connection between thedriving member and the first pressure plate, a shiftable second pressureplate, a friction clutch of variable torsional capacity between thedriven member and the shiftable pressure plate for establishing adriving connection between the driven member and the shiftable pressureplate, the said pressure plates having mutually co-operable cammingmeans thereon for forcing the pressure plates apart and consequentlyincreasing torsional capacity of the friction clutch when the drivingand driven members and consequently the pressure plates tend to rotaterelatively with respect to one another in one relative direction, acasing surrounding the said drive means and rotatable about the axis ofthe overrunning clutch, second connecting means placing the casing indriving connection with the shiftable pressure plate, and a springacting on the pressure plates so as to tend to rotate the platesrelatively with respect to one another in the said one relativedirection, said spring having one end thereof connected to the firstpressure plate and the other end thereof anchored to the casing.

2. An overrunning clutch according to claim 1, wherein the said springis a tension spring arranged circumferentially with respect to therotational axis of the overrunning clutch externally of the said casing,and said one end of the spring is connected to the first pres sure platethough means defining an aperture in said casing.

3. An overrunning clutch according to claim 2 including a brake having aone-way running member in driving connection with the shiftable pressureplate for positively preventing rotation of the shiftable pressure platein one direction of rotation.

4. An overrunning clutch according to claim 3 including mutuallyco-operable stops on the one-way running member and on the firstpressure plate respectively, the stops being arranged so as to limitrotation of the first pressure plate in a direction or rotation opposedto the running direction of rotation of the oneway running member.

5. An overrunning clutch according to claim 4, wherein the said one-wayrunning member is drivingly connected to the casing, and the said secondconnecting means incorporates mutually co-operable ramp faces soarranged that they react to thrust the shiftable second pressure platein a direction away from the friction clutch to permit slip in thefriction clutch when the siftable second pressure plate tends to rotatein a direction of rotation opposed to the running direction of rotationof the one-way running member.

6. An overrunning clutch according to claim 5, wherein the firstpressure plate is a shiftable pressure I t and thes 'd connectin meansor establishin a driving connection between %he driving member a nd thefirst pressure plate is a friction clutch of variable torsional capacityresponsive to action of the said camming means.

1. An overrunning clutch comprising rotatable driving and drivenmembers, drive means operatively interposed between the driving anddriven members, the said means including a first pressure plaTe,connecting means for establishing a driving connection between thedriving member and the first pressure plate, a shiftable second pressureplate, a friction clutch of variable torsional capacity between thedriven member and the shiftable pressure plate for establishing adriving connection between the driven member and the shiftable pressureplate, the said pressure plates having mutually co-operable cammingmeans thereon for forcing the pressure plates apart and consequentlyincreasing torsional capacity of the friction clutch when the drivingand driven members and consequently the pressure plates tend to rotaterelatively with respect to one another in one relative direction, acasing surrounding the said drive means and rotatable about the axis ofthe overrunning clutch, second connecting means placing the casing indriving connection with the shiftable pressure plate, and a springacting on the pressure plates so as to tend to rotate the platesrelatively with respect to one another in the said one relativedirection, said spring having one end thereof connected to the firstpressure plate and the other end thereof anchored to the casing.
 2. Anoverrunning clutch according to claim 1, wherein the said spring is atension spring arranged circumferentially with respect to the rotationalaxis of the overrunning clutch externally of the said casing, and saidone end of the spring is connected to the first pressure plate thoughmeans defining an aperture in said casing.
 3. An overrunning clutchaccording to claim 2 including a brake having a one-way running memberin driving connection with the shiftable pressure plate for positivelypreventing rotation of the shiftable pressure plate in one direction ofrotation.
 4. An overrunning clutch according to claim 3 includingmutually co-operable stops on the one-way running member and on thefirst pressure plate respectively, the stops being arranged so as tolimit rotation of the first pressure plate in a direction or rotationopposed to the running direction of rotation of the one-way runningmember.
 5. An overrunning clutch according to claim 4, wherein the saidone-way running member is drivingly connected to the casing, and thesaid second connecting means incorporates mutually co-operable rampfaces so arranged that they react to thrust the shiftable secondpressure plate in a direction away from the friction clutch to permitslip in the friction clutch when the siftable second pressure platetends to rotate in a direction of rotation opposed to the runningdirection of rotation of the one-way running member.
 6. An overrunningclutch according to claim 5, wherein the first pressure plate is ashiftable pressure plate, and the said connecting means for establishinga driving connection between the driving member and the first pressureplate is a friction clutch of variable torsional capacity responsive toaction of the said camming means.